// mathe
#include <iostream>
#include <cmath>
using namespace std;

int main()
{
	double w;
	double d;
	double h;
	
	w = 25.0;
	d = 18.0;
	
	w = w*2*3.14159/360;
	
	h = d*tan(w);
	
	cout << h <<endl;
		
	return 0;
}